title: Degradation pathway of malachite green in a novel dual-tank photoelectrochemical catalytic reactor.
abstract: A novel dual-tank photoelectrochemical catalytic reactor was designed to investigate the degradation pathway of malachite green. A thermally formed TiO₂/Ti thin film electrode was used as photoanode, graphite was used as cathode, and a saturated calomel electrode was employed as the reference electrode in the reactor. In the reactor, the anode and cathode tanks were connected by a cation exchange membrane. Results showed that the decolorization ratio of malachite green in the anode and cathode was 98.5 and 96.5% after 120 min, respectively. Malachite green in the two anode and cathode tanks was oxidized, achieving the bipolar double effect. Malachite green in both the anode and cathode tanks exhibited similar catalytic degradation pathways. The double bond of the malachite green molecule was attacked by strong oxidative hydroxyl radicals, after which the organic compound was degraded by the two pathways into 4,4-bis(dimethylamino) benzophenone, 4-(dimethylamino) benzophenone, 4-(dimethylamino) phenol, and other intermediate products. Eventually, malachite green was degraded into oxalic acid as a small molecular organic acid, which was degraded by processes such as demethylation, deamination, nitration, substitution, addition, and other reactions.
authors.affiliation: Department of Environmental Engineering, Jinan University, Guangzhou 510630, PR China.
authors.forename: Zenghui
authors.initials: Z
authors.lastname: Diao
authors.forename: Mingyu
authors.initials: M
authors.lastname: Li
authors.forename: Fanyin
authors.initials: F
authors.lastname: Zeng
authors.forename: Lin
authors.initials: L
authors.lastname: Song
authors.forename: Rongliang
authors.initials: R
authors.lastname: Qiu
mesh_terms: D002384:Catalysis; D002412:Cations; D002849:Chromatography, Gas; D002852:Chromatography, Ion Exchange; D004396:Coloring Agents / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004867:Equipment Design; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry / Q000379:methods*; D015203:Reproducibility of Results; D012394:Rosaniline Dyes / Q000032:analysis* / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*
chemical_list: D002412:Cations; D004396:Coloring Agents; D012394:Rosaniline Dyes; D014874:Water Pollutants, Chemical; C005095:malachite green; D010100:Oxygen
keywords: Catalytic degradation; Malachite green; Pathway; Photoelectrochemical catalysis